1. Field of the Invention
The present invention relates to the field of air compressors adapted for use on rail vehicles and, more particularly, to avoiding air compressor failure due to oil pump inlet strainer obstructions.
2. Description of Related Art
Normally, a pneumatic system is provided for a rail vehicle by which the brakes of the rail vehicle are operated. An air compressor is used to supply compressed air to one or more pneumatic units associated with the rail vehicle involved in the operation of the brakes. The air compressor usually consists of a driving unit, such as an electric motor, and a compressor unit, which typically consists of several piston-cylinder arrangements that are driven by a crankshaft. The crankshaft is driven by the driving unit and includes connecting rods to convert the rotating movement of the driving unit into linear movement for each piston to supply compressed air to the downstream units. Screw-type air compressors are also generally known in the field for this purpose and are also included within the scope of the present invention. Furthermore, air compressor units for use on rail vehicles may have a single-stage or a multi-stage construction with at least one low-pressure stage and one high-pressure stage. The air compressors used in the rail vehicle field may be subjected to continuous operation or to frequent on-and-off operation. In either mode of operation, friction during operation of the compressor leads to high heat development. As a result, air compressors predominantly used in the rail vehicle field use oil lubrication to ensure sufficient lubrication and cooling during operation.
Air compressors used on rail vehicles typically have an oil strainer located at the inlet to the air compressor oil pump which is designed to filter large particles, such as carbon debris. The oil strainer prevents entry of particles and other debris into the oil pump and from being passed through the moving components of the air compressor. Over time, the strainer screen becomes increasingly obstructed by the particles and debris being filtered. As the degree of obstruction increases, air compressor damage can occur due to a decrease in oil flow and pressure reaching the moving components. This damage can eventually result in air compressor failure. If the strainer screen becomes 100% obstructed, air compressor failure will occur unless the strainer screen itself fails, allowing oil to pass to the oil pump inlet. One known prior art solution to avoid strainer screen obstruction issues is to entirely remove or omit the strainer screen, but this solution also eliminates the benefits of pre-filtering the lubricating oil used in the air compressor.